Problem: Rearrange the equation so $a$ is the independent variable. $-3a+6b=a+4b$ $b=$
Explanation: To arrive at a correct equation, we have to solve the equation for $b$. $\begin{aligned}-3a+6b&=a+4b\\\\ 2b&=4a\\\\ b&=\dfrac{4a}{2}\\\\ b&=2a\end{aligned}$ The following equation is rearranged so $a$ is the independent variable: $b=2a$